DRC-2011-006009 - 0901a06880236dd9

State of Utah
GARY R. HERBERT
Governor
GREG BELL
Lieutenant Govenwr
Department of
Environmental Quality
Amanda Smith
Executive Diiector
DIVISION OF RADIATION CONTROL
Rusty Lundberg
Diiector
May 26, 2011
CERTIFIED MAIL
RETURNED RECEIPT REOUESTED
FILE
m26m
SR
Mr. David C.-Frydenlund
Vice President, Regulatory Affairs and Counsel
Denison Mines (USA) Corp. (DUSA)
Independence Plaza, Suite 950
1050 Seventeenth Street
Denver, CO 80265
SUBJECT: Chloroform Contamination Investigation. Notice of Violation and ;
Groundwater Corrective Action Order, Docket No: UGW20-01. Plan of Action
and Work Schedule, Request for Additional Information (RFI)
Dear Mr. Frydenlund: .
In May 2010 well TW4-26 was installed downgradient (south) of well TW4-6 with the
purpose to show that the chloroform plume is bound with concentrations less than the
groundwater quality standard (hereafter "GWQS") of 70 |Ltg/l. Monitoring events after TW4-
26 was installed showed chloroform concentrations below the GWQS (less than 13 pg/l) but
the groundwater head data indicated that this well is cross gradient from well TW4-6 and not
downgradient. The 4^^^ quarter 2010 water levels and estimated capture zones map shows a
east to southeast groundwater flow direction from TW4-4 and TW4-6; thereby indicating the
possibility of a zone where the chloroform plume could bypass TW4-26. It was also noted
that this zone of east to southeast groundwater flow is in proximity to the DUSA eastem
property boundary. Thus, there is a potential for the plume to travel under land not owned and
controlled by DUSA. Also, both wells, as of the 4'*" quarter 2010 monitoring event, exceed the
chloroform GWQS.
As a result, there are no wells directly downgradient of TW4-4 and TW4-6 to show that: 1)
the plume is hydraulically bound, 2) that the 70 pg/l chloroform isoconcentration zone is
found hydraulically upgradient of the monitoring well locations and 3) that the plume will
remain under property owned by DUSA. We do recognize that: 1) TW4-4 has been a
pumping well since January 2010 and, 2) in a conference call on May 9, 2011 DUSA verbally
reported that in the 1^^ quarter 2011 monitoring event chloroform concentrations in TW4-6
195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144850 • Salt Lake City, UT 84114-4850
Telephone [phone] • Fax [phone] • T.D.D. [phone]
www.deq.ulah.gor
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Page 2
was below the GWQS, which is encouraging. However, in our conference call on May 17,
2011 we agreed that DUSA would complete one of the following by June 17, 2011:
1. Submit a report for Executive Secretary approval to justify why chloroform
isoconcentration data alone is sufficient to define the full physical extent ofthe
contamination plume downgradient of well TW4-4 and TW4-6 or,
2. Submit for the Executive Secretary approval a plan of action and work schedule to
complete the installation of one or more wells in locations hydraulically downgradient of
wells TW4-4 and TW4-6 to demonstrate the plume is bound and to assure that the plume is
hydraulically being captured in this vicinity. In conjunction with the existing wells, these
new well(s) must^how on a map:
• The 70 pg/l chloroform isoconcentration line remains hydraulically up gradient to the
new well(s) and,
• Groundwater contour lines must show the new well(s) are hydraulically down gradient
to TW4-4 and TW4-6.
Additional Information Request: 1'*, 2"^ 3*^^ and 4**' Quarter 2010 Chloroform
Monitoring Reports
After reviewing the 1^', 2"^*, 3'^^, and 4^^ quarter 2010 chloroform monitoring reports the
following items need to be corrected:
1. The 4^*" quarter 2010 water levels and estimated capture zones map does not show the
locations of wells TW4-23, TW4-24, and TW4-25. Please assure that in the future all
maps submitted will show all well locations, beginning with the 2
Chloroform Monitoring Report, due on September 1, 2011.
nd Quarter, 2011
2. In Appendix G in the 1^', 2"'', 3""^, and 4^'' quarter 2010 chloroform monitoring reports
DUSA has reported wells with incorrect measuring point elevations for depth to
groundwater measurements. Below is a table summarizing the wells with erroneous
measuring point elevations. Please make these corrections.
Summary of Weil Measuring Point Elevations
Well Incorrect elevations reported in the
1^ 2"^ 3^^ and 4^*^ quarter 2010
chloroform monitoring reports,
(feet amsl)
Correct elevations found in DUSA
well asbuilt reports and elevations
used to calculate groundwater
contour maps, (feet amsl)
TW4-1 5622.33 5618.58
TW4-2 5625.00 5624.72
TW4-8 5618.21 5621.40
TW4-12 5624.03 5624.23
TW4-23 5629.00 5651.48
In Appendix G in the 1^', 2"^, 3'"^, and 4'*^ quarter 2010 chloroform monitoring reports,
DUSA has reported wells with incorrect well depths. Below is a table summarizing the
Page 3
wells with incorrect to the corresponding correct well depth. Please make these
corrections.
Summary of Well Depths
Well Incorrect well depths reported in
the 1^2"',3''',and4'%uarter
2010 chloroform monitoring
reports (feet bgs).
Correct well depths found in
well asbuilt reports (feet
bgs).
MW-32 121.3 130
TW4-10 121.3 110
TW4-11 121.3 100
TW4-12 121.3 101.5
TW4-13 121.3 102.5
TW4-14 121.3 93
TW4-16 121.3 142
TW4-18 121.3 137.5
TW4-25 113.5 134.8
Thank you for your cooperation. Please contact Dean Henderson at 801-536-0046 with any
questions.
Sincerely,
Dean C. Henderson, P.G.
Utah Division of Radiation Control
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MAY 26, 2011ISA
Mr. David C. Frydenlund
Vice President, Regulatory Affairs
Denison Mines (USA) Corp. (DUSA) ,
Independance Plaza, Suite 950
1050 Seventeenth Street
Denver, CO 80265
PS'Form 3800.'August 2006 Si3e Reverse for,IhsTructions